The Real Cost of Acquiring a B2B Customer

A campaign can look inexpensive when you divide advertising spend by enquiries. It can look very different after you include the time spent replying, qualifying, writing proposals and setting up the tools.

For a small agency or consultancy, the useful result is a cost per new customer for one clearly defined group of potential purchases, plus a list of what the calculation leaves out. Use your own recorded costs. The example below is fictional and is not a UK or US benchmark.

Define what counts as a lead

Write a short counting rule before opening a report. For this exercise, an enquiry is a genuine request about buying your service. Exclude spam and duplicate messages. Record how you handled an existing customer requesting another project: this guide’s new-customer CAC excludes that work and its revenue.

Follow the potential purchase rather than counting every email sender. Two colleagues discussing one project do not become two opportunities. A downloaded worksheet is not a buying enquiry merely because someone supplied an email address.

Define the subsequent stages too: accepted enquiry, held meeting, opportunity and new customer. An accepted enquiry is one you have agreed to investigate, not a claim that it will convert. A meeting counts when held, not when booked. Choose an explicit win rule, such as a signed contract. These are editorial definitions for this worksheet, not industry standards. Use the qualification guide to make the acceptance decision consistent.

Include media, software and team time

Choose a period in which the enquiry cohort originated and an outcome review date. Then allocate the acquisition costs attributable to that group. Keep a note of the allocation method.

Cost	What to record	Watch for
Media	Ads, placements or relevant paid distribution	Credit notes, agency fees and tax treatment
Tools	The cohort’s share of CRM and other acquisition software	Annual commitment, unused seats, separate add-ons
Team time	Acquisition hours × a documented loaded hourly cost	Owner time, qualification and proposals count too
Setup	The allocated share of migration, training and configuration	Do not charge the full setup to every cohort
Other	Relevant contractors, creative work and allocated acquisition overhead	Exclude costs already counted elsewhere

The calculator asks for the total cost of labour. Calculate hours × your chosen hourly cost outside it and enter the result. Salary cost and the value you assign to owner time are different assumptions: label the method and use it consistently.

Decide whether to allocate setup once, over several periods, or to show it separately. A cash-paid view and an allocated management-cost view answer different questions. Neither should silently mix an annual invoice with one month’s enquiries and call the result a monthly CAC.

Follow one cohort through the funnel

Fictional example: a consultancy reviews 40 unique buying enquiries originating in one quarter. It follows them to an agreed outcome review date, counts 20 accepted enquiries, 10 held meetings, 8 opportunities and 4 new customers. Assume every stage uses the same purchase-level records, with no skipped stages, and all outcomes are resolved for this illustration.

Included cost	Amount, in the selected currency
Media	1,200
Tools, allocated to this cohort	300
Labour: 50 hours × 30	1,500
Allocated setup	400
Other acquisition costs	100
Total	3,500

The calculation is the same arithmetic in GBP or USD; these are two alternative fictional examples, not equivalent purchasing power or an exchange-rate conversion.

• Cost per enquiry = 3,500 ÷ 40 = 87.50.
• Cost per accepted enquiry = 3,500 ÷ 20 = 175.00.
• Cost per held meeting = 3,500 ÷ 10 = 350.00.
• Cost per opportunity = 3,500 ÷ 8 = 437.50.
• Cost per new customer, or cohort CAC = 3,500 ÷ 4 = 875.00.
• Consecutive stage conversions = 50%, 50%, 80%, 50%; enquiry-to-customer conversion = 10%.

Advertising alone divided by customers would show 300. That narrower measure leaves 575 per customer of this example’s included acquisition costs outside the result. It is not wrong to report advertising cost per customer, provided you name it accurately.

The formulas are the editorial method used by this site’s calculator. They are definitions and arithmetic, not an observed performance claim. Open the Funnel Economics Calculator to reproduce every figure.

Compare acquisition cost with contribution margin

Revenue does not show how much is available to recover acquisition cost. For a simple one-project comparison, define contribution as project revenue minus the variable delivery costs you choose to include. State that boundary: contractor work, delivery labour, payment fees and any other variable items must be handled consistently.

If the fictional project’s contribution before acquisition is 1,400 per customer, subtracting CAC of 875 leaves 525. That is a contribution remaining under these assumptions, not net profit. Fixed overhead, tax, refunds, timing of payments and future work may still matter.

Do not insert projected lifetime revenue into a contribution field. This P0 calculator does not estimate LTV, retention, payback time or future sales. Use contribution from the same scope of work or clearly label an alternative horizon.

Know when the data is incomplete

If half the enquiries remain open, the cost per customer recorded so far is provisional. Keep the open count alongside it. Do not treat unresolved enquiries as losses or compare a mature referral cohort with a new advertising cohort as if both were finished.

A zero customer count produces Not enough data, not zero CAC. If one enquiry can create several opportunities, consecutive stage ratios no longer describe a simple nested funnel. The calculator lets you mark stages as incomparable and suppresses those ratios. Keep separate totals and explain the units.

A small cohort can reveal missing cost categories or records. It cannot establish that a channel caused a conversion improvement. Attribution, cancellations and assisted sales need explicit rules; this calculator does not infer them.

UK and US cost notes

Select GBP or USD and enter amounts consistently in that currency. Changing the selection changes the label only. Mixed-currency invoices need a documented exchange-rate source and date before entry.

For UK costs, state whether recoverable VAT is excluded. For US costs, check applicable sales taxes and the actual invoice. The HMRC VAT guidance describes when VAT may be reclaimed; it does not establish your business’s eligibility. This guide offers no tax determination for any operator or US state.

Your next step

Choose one completed cohort, write its counting and cost-allocation rules, and reproduce the example using your own totals in the calculator. If the missing input is the meaning of an accepted enquiry, start with the Lead Qualification Sheet.